Hydrogen liquefaction device

ABSTRACT

An example hydrogen liquefaction apparatus is disclosed. The apparatus includes an outer container; a liquefaction container positioned at least partially within the outer container; a heat pipe positioned within the liquefaction container. The head pipe includes a condensing portion, an evaporating portion, an inner tube portion containing a working fluid and operatively coupling the condensing portion to the evaporating portion, and an outer tube portion surrounding the inner tube portion and defining a dual tube region between the outer tube and the inner tube. Also included is a cryocooler in thermal communication with the liquefaction container, a pre-cooling tube, and an ortho-para converting part having a catalyst configured to induce an ortho-para conversion of gaseous hydrogen within the pre-cooling tube.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0016990, filed on Feb. 5, 2015, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates to a hydrogen liquefaction device, and more particularly, to a hydrogen liquefaction device using a dual tube type heat pipe, which utilizes cooling energy of a cryocooler via dual tube type heat pipe to liquefy gaseous hydrogen. A method of liquefying hydrogen is also disclosed herein.

Recently, hydrogen energy has emerged as a potential solution to air pollution and climate change caused by excessive use of fossil fuels. Utilizing fuel sources that are not hydrocarbon based can help reverse the problems of pollution and climate change that may otherwise continue unchecked. Hydrogen is advantageous because it can be obtained from water. In addition, unlike hydrocarbon fuels, when hydrogen energy is combusted it only creates water as a byproduct. No carbon dioxide is emitted, for example.

In order to effectively utilize hydrogen as energy source, it should be made convenient to transport and store. These goals may be achieved by, for example, reducing the volume of the hydrogen via a densification process. Among the methods for reducing a volume of hydrogen and storing hydrogen, a method of liquefying and storing the hydrogen in a liquid phase has the largest storage energy.

Among methods for liquefying gaseous hydrogen, the Linde-Hampson cycle, Claude cycle, and similar cycles are known. However, these liquefying cycles require large-scale hydrogen liquefaction systems that may not be suitable for liquefying and/or transporting smaller amounts of hydrogen. The ability to liquefy and/or transport small amounts of hydrogen is an important aspect of increasing hydrogen consumption in different sectors of the global economy.

As a result, a need exists for improving the performance and stability of hydrogen liquefaction processes. This is particularly true for those processes employing a cryocooler.

SUMMARY

In one example embodiment, a hydrogen liquefaction apparatus is disclosed. The apparatus includes an outer container; a liquefaction container positioned at least partially within the outer container; a heat pipe positioned within the liquefaction container. The head pipe includes a condensing portion, an evaporating portion, an inner tube portion containing a working fluid and operatively coupling the condensing portion to the evaporating portion, and an outer tube portion surrounding the inner tube portion and defining a dual tube region between the outer tube and the inner tube. Also included is a cryocooler in thermal communication with the liquefaction container and configured to cool the condensing portion of the heat pipe; a pre-cooling tube positioned at least partially within the dual tube region and comprising an inlet port for receiving gaseous hydrogen and an outlet port for discharging gaseous hydrogen into the liquefaction container; and an ortho-para converting part positioned at least partially within the pre-cooling tube, the ortho-para converting part comprising a catalyst configured to induce an ortho-para conversion of gaseous hydrogen within the pre-cooling tube.

In another example embodiment, a method of liquefying hydrogen is disclosed. The method includes, for example, providing a liquefaction container positioned at least partially within an outer container, and providing a heat pipe within the liquefaction container, the heat pipe including a condensing portion, an evaporating portion, an inner tube portion, and an outer tube portion, wherein the inner and outer tube portions for a dual tube region. The method includes introducing gaseous hydrogen into a pre-cooling tube positioned within the dual tube region; ortho-para converting the gaseous hydrogen within the pre-cooling tube; and collecting liquid hydrogen within the liquefaction container.

In yet another example embodiment, a heat pipe is disclosed having a condensing portion; an evaporating portion; an inner tube portion containing a working fluid and operatively coupling the condensing portion to the evaporating portion; an outer tube portion surrounding the inner tube portion and defining a dual tube region between the outer tube and the inner tube; a cryocooler in thermal communication with the condensing portion; a pre-cooling tube positioned at least partially within the dual tube region and comprising an inlet port for receiving gaseous hydrogen and an outlet port for discharging gaseous hydrogen into the liquefaction container; and an ortho-para converting part positioned at least partially within the pre-cooling tube, the ortho-para converting part comprising a catalyst configured to induce an ortho-para conversion of gaseous hydrogen within the pre-cooling tube.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic view showing an example structure of a hydrogen liquefaction apparatus using a dual tube type heat pipe.

FIG. 2 is a diagrammatic view of an example structure of a dual tube region of a heat pipe in a hydrogen liquefaction apparatus using a dual tube type heat pipe.

DETAILED DESCRIPTION

Hydrogen liquefaction device and methods of liquefying hydrogen are disclosed herein. In some example embodiments, the hydrogen liquefaction device utilizes a dual tube type heat pipe as described in detail below with reference to the accompanying drawings. While the present disclosure is shown and described in connection with example embodiments, various modifications can be made without departing from the spirit and scope of the invention.

FIG. 1 a diagrammatic view showing an example structure of a hydrogen liquefaction apparatus using a dual tube type heat pipe and FIG. 2 is a diagrammatic view of an example structure of a dual tube region of a heat pipe in a hydrogen liquefaction apparatus using a dual tube type heat pipe.

Referring to FIGS. 1 and 2, an example embodiment of a hydrogen liquefaction apparatus is depicted. The hydrogen liquefaction apparatus utilizes a dual tube type heat pipe design. The device may include, for example, an external container 10, a liquefaction container 20, a cryocooler 30, a heat pipe 40, a pre-cooling tube 50, and an ortho-para converting part 51.

The external container 10 is configured to contain the liquefaction container 20, heat pipe 40, pre-cooling tube 50, and ortho-para converting part 51. The external container 10 may take any form, but as shown in FIG. 1 has a cylindrical shape with an open upper end to enable another element such as the liquefaction container 20 and the like to be received therein. The open upper end of the external container 10 may be hermetically covered with an upper cover 12.

A cryocooler 30 may be installed on the upper cover 12 or on the external container 10 directly. Cryocooler 30 may be a standalone cooler, such as, for example, a Stirling-type cooler, a Gifford-McMahon-type cooler, a pulse-tube refrigerator, or a Joule-Thomson-type cooler. Any other suitable type of cooler may be used, and the disclosure herein is not intended to be limited to a particular type of cryocooler. Cryocooler 30 may supply cooling energy to the heat pipe 40 placed in the liquefaction container 20. The cryocooler 30 may supply the cooling energy which is sufficient to cool the liquefaction container 20 to a temperature of 20K or less.

A heat insulating layer 11 and/or a multi-layer insulating material (not shown) may be included between the external container 10 and the liquefaction container 20 to reduce heat invasion generated in the radial direction caused by the environment external to the external container 10.

Additionally, the space between the external container 10 and the liquefaction container 20 may be provided in a vacuum state to form the heat insulating layer 11. The heat insulating layer 11 performs a function of blocking convective heat transfer otherwise caused by air as well as conductive heat transfer to/from the external container 10. A multilayered heat insulating material layer can be formed by overlapping the heat insulating material surrounding the liquefaction container 20 and, for example, performs the function of reducing heat radiation to/from the liquefaction container 20 and the external container 10.

The liquefaction container 20 is a cylindrical container provided in the external container 10, an upper end of the liquefaction container is fixed to the upper cover 12 or to a support (not shown) connecting a bottom surface of the external container 10 and a bottom surface of the liquefaction container 20 to each other. In order to reduce heat invasion in the axial direction from the upper cover 12, the liquefaction container 20 may be provided with a blocking layer formed therein or a heat insulating layer disposed thereon and may be then fixed to the upper cover 12. According to another embodiment, in addition, it is possible to install the liquefaction container through a separate support acting as a medium.

The heat pipe 40 may be positioned in the liquefaction container 20 for receiving the extremely low temperature cooling energy from the cryocooler 30. In the embodiments of FIGS. 1 and 2, the heat pipe 40 includes a condensing part 41, an evaporating part 42, an outer tube 43, and an inner tube 44 provided between the condensing part 41 and the evaporating part 42 in the form of a dual tube.

The condensing part 41 of the heat pipe 40 is in contact with the cryocooler 30 to transfer the cooling energy of the cryocooler 30 to the evaporating part 42 of the heat pipe 42 through working fluid acting as a medium. The evaporating part 42 liquefies gaseous hydrogen, which flows into the liquefaction container 20, with the cooling energy transferred from the condensing part 41 by means of the working fluid. Cooling fins 41 a and 42 a are provided in the condensing part 41 and the evaporating part 42, respectively, to promote the heat transfer in the heat pipe 40.

The outer tube 43 is spaced from the inner tube 44 and surrounds the inner tube 44. As a result, a dual pipe region 45 is formed in the space between the outer tube 43 and the inner tube 44. In some embodiments, the dual pipe region 45 is filled, at least partially, with solid nitrogen. Solid nitrogen is a cooling material. To obtain solid nitrogen, gaseous nitrogen flows into and is cooled in this region so that the gaseous nitrogen is phase-changed to solid nitrogen (SN2) to at least partially fill this region.

The pre-cooling tube 50 is provided in the dual pipe region 45. The pre-cooling tube 50 is spaced apart from the outer tube 43 and the inner tube 44 in the dual pipe region 45, and is extended and wound around the inner tube 44 in the form of a coil. The pre-cooling tube 50 may be wound around the inner tube 44 in other orientations as well, depending on the implementation. The pre-cooling tube 50 is connected to the outer tube 43 via an upper inlet port 52 and a lower outlet port 54. The upper inlet port 52 is connected to a gaseous hydrogen transferring tube 62 and the lower outlet port 54 is connected to a liquefaction guide tube 55.

In the embodiments of FIGS. 1 and 2, the ortho-para converting part 51 is provided with a catalyst causing an ortho-para conversion is formed in the pre-cooling tube 50. The ortho-para converting part 51 may be formed over an entire length of the pre-cooling tube 50 or may be formed over only a part of the pre-cooling tube. Due to the ortho-para converting part 51 formed in the pre-cooling tube 50, when gaseous hydrogen passes through the pre-cooling tube 50, gaseous hydrogen is simultaneously subjected to a pre-cooling and the ortho-para conversion.

The liquefaction guide tube 55 is extended toward an outer surface of the evaporating part 42 of the heat pipe 40 to guide gaseous hydrogen GH2 discharged through the liquefaction guide tube 55 to the evaporating part 42 of the heat pipe 40. The orientation of liquefaction guide tube 55 shown in FIG. 1 is merely an example orientation. Any orientation may be used to guide gaseous hydrogen to the evaporating part 42 of the heat pipe 40.

A cooling material entering port 46 is formed on the outer tube 43 for allowing gaseous nitrogen to flow into the dual pipe region 45 between the outer tube 43 and the inner tube 44. The cooling material entering port 46 is connected to a gaseous nitrogen transferring tube 64. Gaseous nitrogen entered into the dual pipe region 45 is cooled and then phase-changed to solid nitrogen SN2, and the dual pipe region is at least partially filled with solid nitrogen. In some embodiments the dual pipe region is partially filled with solid nitrogen. In other embodiments the dual pipe region is fully filled with solid nitrogen. In yet other embodiments the dual pipe region is filled with a combination of solid, liquid, and/or gaseous nitrogen.

The inner tube 44 of the heat pipe 40 is filled with gaseous hydrogen acting as working fluid. For achieving the above, the heat pipe 40 may be provided with a working fluid entering passage for enabling gaseous hydrogen, which is the working fluid, to fill an inner space of the inner tube 44 or may be manufactured such that an inner space of the inner tube is hermetically filled with working fluid.

The gaseous hydrogen transferring tube 62 for transferring gaseous hydrogen from the outside to the liquefaction container 20 and the gaseous nitrogen transferring tube 64 for transferring gaseous nitrogen are extended in the liquefaction container 20.

The gaseous hydrogen transferring tube 62 is connected to the upper inlet port 52 of the pre-cooling tube 50 and the gaseous nitrogen transferring tube 64 is connected to the cooling material entering port 46 to supply gaseous nitrogen to the dual tube region 45 between the outer tube 43 and the inner tube 44.

Valves (not shown) may be installed on the gaseous hydrogen transferring tube 62 and the gaseous nitrogen transferring tube 64 for controlling transferring of gaseous hydrogen and gaseous nitrogen to the upper inlet port 52 and the cooling material entering port 46.

Meanwhile, a liquid hydrogen transferring tube 68 is connected to a bottom surface of the liquefaction container 20 for transferring liquid hydrogen, which is liquefied in the liquefaction container 20, to the outside.

An example process for liquefying hydrogen performed by, for example, the device of FIGS. 1 and 2, is described herein.

In the initial stage of operating the hydrogen liquefaction apparatus, the cooling energy is transferred from the cryocooler 30 to the condensing part 41 of the heat pipe 40. Some of gaseous hydrogen transferred through the gaseous hydrogen transferring tube 62 is supplied to an inside of the inner tube 44 of the heat pipe 40 via a working fluid entering passage 48. Gaseous hydrogen supplied to an inside of the inner tube 44 and acting as working fluid flows upward and downward in the heat pipe 40 and transfers the cooling energy of the cryocooler 30, which was transferred to the condensing part 41, to the evaporating part 42.

Meanwhile, gaseous nitrogen transferred through the gaseous nitrogen transferring tube 64 is supplied to the dual pipe region 45 between the outer tube 43 and the inner tube 44 through the cooling material entering port 46. Gaseous nitrogen entered into the dual pipe region 45 receives the cooling energy and is then phase-changed to solid nitrogen.

Gaseous hydrogen transferred through the gaseous hydrogen transferring tube 62 flows into the pre-cooling pipe 50 via the upper inlet port 52. A time at which gaseous hydrogen flows into the pre-cooling tube 50 may be controlled by controlling a valve. While moving along the pre-cooling tube 50, gaseous hydrogen entered into the pre-cooling pipe 50 is heat-exchanged with ambient solid nitrogen and then pre-cooled. Simultaneously, gaseous hydrogen passes through the ortho-para converting part 51, is in contact with the ortho-para catalyst, and is converted to para hydrogen, which is an equilibrium state corresponding to approximately 77K, by performing the ortho-para conversion. Gaseous hydrogen is subsequently transferred to the liquefaction guide tube 55 through the lower outlet port 54, and the liquefaction guide tube 55 guides gaseous hydrogen toward the evaporating part 42 of the heat pipe. Since gaseous hydrogen is in contact with the evaporating part 42 of the heat pipe after pre-cooled and converted to para hydrogen, gaseous hydrogen is rapidly liquefied to form a liquid hydrogen drop.

Liquid hydrogen obtained by a contact between gaseous hydrogen and the evaporating part 42 is fallen by its weight and is collected to a lower portion of the liquefaction container 20, and the liquid hydrogen collected in the lower portion of the liquefaction container 20 is discharged to the outside through the liquid hydrogen transferring tube 68.

As described above, according to the present invention, while passing through the dual tube region 45 filled with solid nitrogen via the pre-cooling tube 50, gaseous hydrogen is heat-exchanged and passes the ortho-para catalyst so that gaseous hydrogen is pre-cooled and ortho-para converted, and is then in contact with the evaporating part 42 and is liquefied. As a result, gaseous hydrogen of room temperature of 300K is in direct contact with the cryocooler 30 to prevent a thermal load of the cryocooler from being rapid increased. In other words, the present invention is advantageous in that an initial thermal load of the cryocooler can be reduced.

In addition, even when an operation of the cryocooler 30 is halted, it is possible to retard the boil-off state in which liquid hydrogen in the liquefaction container 20 is gradually evaporated by a heat invasion from the outside until solid nitrogen with which the dual tube region 45 of the heat pipe 40 is filled is phase-changed to liquid nitrogen.

In some embodiments, the heat pipe and the ortho-para converting part are combined into one unit.

According to one embodiment, while passing through the pre-cooling tube placed in the dual tube region of the heat pipe, which is filled with solid nitrogen, and the ortho-para converting part, gaseous hydrogen is pre-cooled and ortho-para converted. For example, gaseous hydrogen is pre-cooled to a temperature of 77K and is ortho-para converted to an equilibrium state of 77K. Then, gaseous hydrogen is in contact with the evaporating part of the heat pipe and is liquefied to form liquid hydrogen. Due to the above, gaseous hydrogen having a temperature of 300K is in direct contact with the evaporating part of the heat pipe having a temperature of 20K to prevent a load of the refrigerator from being rapidly increased. As a result, an initial thermal load of the refrigerator can be reduced.

According to another embodiment, in the state where an operation of the cryocooler is halted, an evaporation of liquid hydrogen is retarded for the time during which solid nitrogen is phased-changed to liquid nitrogen. Thus, it is possible to enhance the liquid hydrogen storage performance of the hydrogen liquefaction apparatus.

It will be apparent to those skilled in the art that various modifications can be made to the above-described exemplary embodiments of the present disclosure without departing from the spirit or scope of the invention. Thus, it is intended that the present disclosure covers all such modifications provided they come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A hydrogen liquefaction apparatus, comprising: an outer container; a liquefaction container positioned at least partially within the outer container; a heat pipe positioned within the liquefaction container and comprising a condensing portion, an evaporating portion, an inner tube portion containing a working fluid and operatively coupling the condensing portion to the evaporating portion, and an outer tube portion surrounding the inner tube portion and defining a dual tube region between the outer tube and the inner tube; a cryocooler in thermal communication with the liquefaction container and configured to cool the condensing portion of the heat pipe; a pre-cooling tube positioned at least partially within the dual tube region and comprising an inlet port for receiving gaseous hydrogen and an outlet port for discharging gaseous hydrogen into the liquefaction container; and an ortho-para converting part positioned at least partially within the pre-cooling tube, the ortho-para converting part comprising a catalyst configured to induce an ortho-para conversion of gaseous hydrogen within the pre-cooling tube.
 2. The hydrogen liquefaction apparatus of claim 1, comprising a gaseous hydrogen transfer tube operatively connected to the inlet port of the pre-cooling tube and configured to supply gaseous hydrogen to the pre-cooling tube.
 3. The hydrogen liquefaction apparatus of claim 1, comprising a liquefaction guide tube operatively connected to the outlet port of the pre-cooling tube and configured to transfer liquid hydrogen from the pre-cooling tube to the liquefaction container.
 4. The hydrogen liquefaction apparatus of claim 1, wherein the pre-cooling tube is configured to pre-cool and ortho-para convert gaseous hydrogen.
 5. The hydrogen liquefaction apparatus of claim 1, wherein the pre-cooling tube is configured to pre-cool the gaseous hydrogen to an equilibrium state of about 77 degrees Kelvin.
 6. The hydrogen liquefaction apparatus of claim 1, wherein the evaporating portion causes the gaseous hydrogen to liquefy upon contact.
 7. The hydrogen liquefaction apparatus of claim 1, wherein the dual tube region is at least partially filled with solid nitrogen.
 8. The hydrogen liquefaction apparatus of claim 6, wherein the solid nitrogen is formed via cooling of gaseous or liquid nitrogen within the dual tube region.
 9. The hydrogen liquefaction apparatus of claim 1, wherein the outlet port is configured to expel gaseous hydrogen toward a surface of the evaporating portion.
 10. The hydrogen liquefaction apparatus of claim 1, wherein the ortho-para converting part is provided along the entire pre-cooling tube.
 11. The hydrogen liquefaction apparatus of claim 1, wherein the inlet port comprises a valve for controlling the transfer of gaseous hydrogen.
 12. The hydrogen liquefaction apparatus of claim 1, comprising a liquid hydrogen transferring tube configured to transfer liquid hydrogen from the liquefaction container.
 13. The hydrogen liquefaction apparatus of claim 1, comprising a nitrogen transferring tube configured to transfer gaseous or liquid nitrogen into the dual tube region.
 14. The hydrogen liquefaction apparatus of claim 1, wherein the evaporating portion of the heat pipe is configured to maintain a temperature of about 20 degrees Kelvin.
 15. A method of liquefying hydrogen, comprising providing a liquefaction container positioned at least partially within an outer container; providing a heat pipe within the liquefaction container, the heat pipe comprising a condensing portion, an evaporating portion, an inner tube portion, and an outer tube portion, wherein the inner and outer tube portions for a dual tube region; introducing gaseous hydrogen into a pre-cooling tube positioned within the dual tube region; ortho-para converting the gaseous hydrogen within the pre-cooling tube; and collecting liquid hydrogen within the liquefaction container.
 16. The method of claim 15, comprising cooling a condensing portion of the heat pipe via a cryocooler.
 17. The method of claim 15, comprising filling at least a portion of the dual tube region with solid nitrogen.
 18. The method of claim 17, wherein filling further comprises converting gaseous or liquid nitrogen into solid nitrogen within the dual tube region.
 19. The method of claim 15, comprising liquefying the gaseous hydrogen upon thermal contact with the evaporating portion of the heat pipe.
 20. A heat pipe, comprising: a condensing portion; an evaporating portion; an inner tube portion containing a working fluid and operatively coupling the condensing portion to the evaporating portion; an outer tube portion surrounding the inner tube portion and defining a dual tube region between the outer tube and the inner tube; a cryocooler in thermal communication with the condensing portion; a pre-cooling tube positioned at least partially within the dual tube region and comprising an inlet port for receiving gaseous hydrogen and an outlet port for discharging gaseous hydrogen into the liquefaction container; and an ortho-para converting part positioned at least partially within the pre-cooling tube, the ortho-para converting part comprising a catalyst configured to induce an ortho-para conversion of gaseous hydrogen within the pre-cooling tube. 